Shape Hunting - Circles, Semicircles, Ellipses

One [Music] more up. [Music] What's special about a circle? It's a closed curve with no beginning or ending. Every point on a circle is the same distance from one point, the center. How are these two circles alike? They have the same center. What makes one circle larger than another? A longer radius, diameter, and circumference. Now, let's go hunting for [Music] circles. Heat. Heat. Goodbye. [Music] Now you know about circles. Remember a circle has a radius, a diameter, and a circumference. [Music] What's a semicircle? Half a circle. The diameter of a circle divides it into two semicircles. Sometimes you see a circle as the outline of a sphere and a semicircle as the outline of half a sphere, a hemisphere. Semi hemi. What are we hunting for? Semicircles and hemispheres. [Music] Now you know a semicircle is half a circle and makes the outline of a half a [Music] sphere. What's this shape? An ellipse. It's different from a circle in one important way. To draw a circle, you need only one point, the center. The center is the same distance from every point on the circle. But there's no center that's the same distance from all the points on an ellipse. Now, let's go ellipse hunting. All [Music] right. [Music] Yeah, let's do it. [Music] Now you know how to find ellipses. [Music] Hey, hey, hey. [Music]